Circuit interrupter of the single-bushing type with canted terminal-bushing construction



Jan. 5, 1965 R. E. FRIEDRICH ETAL 3,164,703

CIRCUIT INTERRUPTER OF THE SINGLEBUSHING TYPE WITH CANTEDTERMINAL-BUSHING CONSTRUCTION 6 Sheets-Sheet 1 Filed Sept. 15, 1959 rr"| V /Zt Fxg I.

WITNESSES I NVENTORS Robert E. Friedrich, Curl G. Lentjes m 8 GeorgeB.Cushinq Jan. 5, 1965 R. E. FRIEDRICH ETAL cmcurr INTERRUPT 3,164,703ER OF THE SINGLE-BUSHING TYPE WITH CANTED TERMINAL-BUSHING CONSTRUCTIONFiled Sept. 15, 1959 6 Sheets-Sheet 2 1965 R. E. FRIEDRICH ETAL3,164,703

CIRCUIT INTERRUPTER OF THE SINGLE-BUSHING TYPE WITH CANTEDTERMINAL-BUSHING CONSTRUCTION Filed Sept. 15, 1959 6 Sheets-Sheet 5A\\\\\\\\\\\\\\' F i 3(;

1965 R. E. FRIEDRICH ETAL 3,1 4, 03

BUSHING TYPE w:

CIRCUIT INTERRUPTER OF THE SINGLE- CANTED TERMINAL-BUSHING CONSTRUCTION6 Sheets-Sheet 6 Filed Sept. 15, 1959 Fig.4.

O I r United States Patent Ofifice 3,154,703 Patented Jan. 5, 1965CIRCUIT HNTERRUPTER 0F THE SlNG'LEdiUSi-i- ENG TYPE WITH CANTEDTERMINAL-BUSHRNG CUNSTRUCTEDN Rohert E. Friedrich, Baldwin, Carl G.Lentjes, Churchiil, and George B. Cashing, Penn Hills, Pa, assignors toWestinghouse Electric Corporation, East Pittsburgh, Pa., a corporationof Pennsylvania Filed Sept. 15, 1&59, Ser. No. 843,133 '7 (Ilairns. (Cl.Hid-Md) This invention relates to circuit interrupters in general, and,more particularly, to improved mounting constructions andarc-extinguishing arrangements therefor.

As well known by those skilled in the art, in the tanktype oil circuitinterrupter a grounded tank is employed with two terminal bushingsextending thereinto and supporting at the lower ends thereofarc-extinguishing units bridged by the usual bridging bar. It is, ofcourse, obvious that the terminal bushings, of which there are two foreach pole-unit, constitute expensive items of electrical equipment, andit would be of advantage, both as regards space and cost, to eliminateone of the two terminal bushings. The use of terminal bushings, however,extending into a grounded tank, or casing, permits the utilization ofinexpensive through-type current transformers. Such through-type, orring-type current transformers may merely encircle the terminal bushingadjacent the central grounded portion thereof and are, as well known,considerably less expensive than woundtype current transformers, whichmust be wound with adequate insulation to withstand line-to-groundvoltage.

The present invention relates to interrupting apparatus in which only asingle terminal bushing is employed, as contrasted to the use of twoterminal bushings for tanktype circuit interrupters. Thus, theinexpensive ringtype current transformer may be utilized, and aconventional, stock-item bushing may be used without specialconstruction. Accordingly, the term circuit-interrupter of thesingle-bushing type means herein a circuit interrupter using only asingle terminal bushing, which may be of a conventional standard type.

In United States Patent 2,866,045, issued December 23, 1958, to WinthropM. Leeds, and assigned to the assignee of the instant application, thereis disclosed and described a number of single-bushingcircuit-interrupting structures. There is a disadvantage to the amountof space taken up by the particular disposition of the circuitinterrupting structure of the Leeds device, and it is a general objectof the present invention to retain a number of the advantages of thesingle-terminal-bushing construction of the interrupting devicedisclosed in the Leeds patent, yet nevertheless rearranging thedisposition of the device to result in a considerable saving ofhorizontal ground space.

A more specific object of the present invention is the provision of aplurality of compact pole units arranged in a space-saving manner, andadapted for simultaneous operation from a single operating mechanism.

A further object of the present invention is the provision of asinglederminahbustring-type of circuit interrupter, in which preferablythe interrupting casing is dis interrupting structure as an internalfault, as contrasted with an external fault.

Yet a further object of the present invention is the pro vision of animproved single-terminalbushing-type of circuit interrupter in which theseveral interrupting elements thereof are readily adaptable for removalfrom the circuit-interrupter housing with a minimum of effort.

Yet another object of the present invention is the provision of animproved circuit-interrupting structure in which the arrangement is suchas to facilitate the convec-' tion flow of the arc-extinguishing mediumto permit its cooling at an upper metallic closure member for theinterrupter casing.

Another object of the present invention isthe provision of an improvedcircuit interrupter of the single-terminalbushing type, in which theoperating mechanism is such as to readily adapt the device formultiple-pole operation.

Another object of the invention is the provision of an improvedcircuit-interrupting structure of the singletcrminal-bushing-type, inwhich use is made of an effective arc'extinguishing gas having a highdielectric strength, such as sulfur hexafiuoride (SP whereby thedistances between internal parts, at opposite potential, may be aminimum, and the terminal-bushing construction is so configured as toresult in a considerable horizontal saving of ground space.

Generally, the present invention is concerned with a single-bushing typeof circuit interrupter including a grounded mechanism housing supportingboth an outwardly extending interrupting means and also a cantedterminal bushing. This results in a space-saving arrange ment. Inaddition, the invention is concerned with a fluid puffer-typeinterrupter in which a fluid blast is i brought about by relativemovement between a piston and a cylinder. Such a self-containedinterrupter has particular advantages as applied to the foregoinginterrupter construction.

To reflect faults associated with the interrupter as. internal faults,as contrasted with external faults, a .pair of current transformers aremounted upon opposite sides of the grounded mechanism housing and soelectrically constructed as to force fiashovers to pass to groundbetween them.

Further objects and advantages will readily become apparent upon readingthe following specification, taken in conjunction with the drawings, inwhich:

FIGURE 1 is an end elevational view of the three-polecircuit-interrupting assemblage with a differential protec-.

tive relay system incorporated in the drawing to illustrate thefunctioning of the current-transformer arrangement, the contactstructure being diagrammatically indicated in the closed-circuitposition;

FIG. 2 is a front elevational View of the three-pole FIG. 1 thereof, thereference numeral 1 generally designates a single-bushing-type ofcircuit interrupter supported upon a grounded metallic framework 2. Withreference to FIG. 2, it will be noted that three such singleterminal-bushing-types of circuit interrupters may be mounted upon thesame grounded frame 2, and a common mechanism compartment 3 may beprovided. The mechanism disposed Within the mechanism compartment 3 maybe of any conventional type, and, when operated, serves Jr to effect therotation of a horizontally extending operating rod 4 which interconnectsthe three pole-units 1.

With reference to FIG. 1, it will be noted that generally eachsingle-terminal-bushing-type of circuit interrupter 1 includes anupstanding insulating interrupter casing 5, a grounded mechanism housing6, supported by the upstanding framework 2, and a single terminalbushing, generally designated by the reference numeral 7. The terminalbushing 7 may be of a conventional type, such as an oil-filled type, orit may be of the gas-filled type, such as set forth in United Statespatent application filed December 2, 1959, Serial No. 856,775, by RobertE. Friedrich and James H. Frakes, and assigned to the assignee of theinstant application.

Supported upon the mechanism housing 6 and disposed below theinterrupter casing is a first current transformer 8, so arranged as toensure that any faults, or breakdowns occurring along the outer or innerwalls of the insulating casing 5 will pass through the first currenttransformer 8 to ground by way of the framework 2.

A second current transformer 9 is associated with the canted terminalbushing 7 and has the cover plate 10 thereof disposed at such a remotedistance from the outer end 11 of the terminal bushing 7, that anybreakdown occurring along either the inside or outside surface of theporcelain weatherproof shell 12 will strike to the supporting flange 13(FIG. 3C) and likewise be carried to ground through the second currenttransformer 9. As will be more fully brought out hereinafter, it isdesired to have any fault condition associated with thecircuitinterrupting assemblage 1 sensed as an internal fault condition,as contrasted with an external fault condition. In other words, it isdesired to have any fault condition associated with thecircuit-interrupting assemblage 1 reflected as an internal faultcondition so that the remote circuit interrupters 14, 15 will also open,together with the opening of circuit interrupter 1.

With reference to FIGS. 3B and 30, it will be noted that the mechanismhousing 6, at ground potential, is somewhat of an upwardly extending Uconfiguration. The left leg of the U configuration, indicated by thereference numeral 17 (FIG. 38), supports the upstanding insulatingcasing 5, which is preferably formed from porcelain. The right leg 18 ofthe generally U-shaped mechanism housing 6 supports the terminal bushing7 by the mounting flange 13 thereof. Crank means, generally designatedby the reference numeral 2t includes a rotatable shaft 21, which extendswithin the interior of the mechanism housing 6 in a gas-tight manner,and is keyed to an internally disposed crank-arm 22, piv-otallyconnected at 23 to a pair of operating rods 24. The operating rods 24are formed of insulating material, and have lower rod-ends 24a ofmetallic material.

, The rotatable operating shaft 21 may constitute an extension of therotatable shaft 4 of FIG. 2, which is rotated by the actuation of themechanism disposed interiorly within the mechanism compartment 3. Thus,clockwise rotation of the operating shaft 21, as viewed in FIG. 3B,effects corresponding clockwise rotative movement of the crank-arm 22,and hence downward opening motion of the pair of insulating operatingrods 24. The upper ends of the operating rods 24 have rod-ends 2417(FIG. 4), which are pivotally connected as at 25 to lugs 26, afiixeddiametrically on opposite sides of a movable metallic puffer operatingcylinder 27. At the upper end of the puffer cylinder 27 is an inwardlyextending flange portion 27a, to which is bolted, by bolts 23, a movablecontact support 29. The movable contact support 29 is, in turn, boltedby bolts 30, FIG. 3A, to a movable contact, generally designated by thereference numeral 31. The movable contact 31 includes a plurality ofcircumferentially spaced flexible spring fingers 32, and a bayonet-typearcing contact 33. The movable fingers 32 and the arcing contact 33 makecontacting engagement with a downwardly extending, rod-shaped relativelystationary contact 34. The lower tip portion of the rod-shapedstationary contact 34 is hollowed, as at 34a, to accommodate the upperextremity of the arcing contact 33, as shown in FIG. 3A.

The upper end of the relatively stationary contact 34 is adjustablythreadedly secured within a clamp 35, which is bolted as at 36, to anannular mounting plate 37. The mounting plate 37 is secured, by bolts38, to a mounting flange ring 39, cemented to the upper end of thecasing 5. in addition, an upper closure inspection plate 40 is provided,being bolted by bolts 41 to the annular mounting plate 37.

Movable contact support 29 has an upper extension 42, to which is boltedby bolts, no shown, an insulating orifice member 43. The movable contactsupport 29 also has apertures 44 (FIG. 4) provided therethrough, throughwhich an upward moving blast of gas passes from a compression chamber,generally designated by the reference numeral 45.

The compression chamber 45 is provided by the coaction between thepuffer cylinder 27 and a fixed piston 46. It will be obvious, therefore,that relative motion between the operating cylinder 27 and the fixedpiston 46 will result in a raising of the pressure within thecompression chamber 45 and an ejection of compressed fluid upwardly fromthe chamber 45, through the apertures 44, and through the orificeopening 47 of the orifice sleeve 43 to effect extinction of the are 19(FIG. 4) drawn therethrough.

Although FIG. 4 illustrates the fully open circuit position of theinterrupter 1, nevertheless, for purposes of illustration, the drawn are19 has been drawn into the figure, together with arrows 16 indicatingthe gas blast. Arc extinction quickly follows.

The fixed piston 46 constitutes the upper extremity of an insulatingpedestal, generally designated by the reference numeral 48, which ismounted, as at 49 (FIG. 3B), to a lower plate portion 50 of themechanism housing 6. A removable cover 51 is bolted, by bolts 52, to thesame plate portion 513, and permits downward withdrawal of theinsulating pedestal 48 for maintenance and service operations, as morefully brought out hereinafter.

Adjacent the lower end of the insulating cylindrical pedestal 48 is acutout portion 53 which accommodates a tubular conductor 54, having anelbow connection, as at 55, to a horizontally extending tubularconductor 56, which is attached to the lower end 57 of the terminalbushing 7.

Secured, as by a press fit, to the upper end of the tubular conductor 54is a contact support 58, having integrally formed flexible stationaryfingers 59. Contacting, in sliding engagement, with the stationaryfingers 59 is a downwardly extending rod-shaped portion 60 of themovable contact structure 31. As shown in FIG. 3A, the contact support58 is secured, as by stud bolts 61, to the fixed piston 46, the latterconstituting an upper closure plate for the tubular pedestal support 48.In addition, one-way acting valves 62 are provided, being spring-biasedto their open position, as shown, to permit the ready passage of fluidupwardly from the region 63 (FIG. 3A) interiorly of the pedestal support48 and into the compression region 45 in the closed-circuit position ofthe interrupter. However, upon downward opening movement of theoperating cylinder 27, the several valves 62 will, of course, close byvirtue of the gas pressure present within region 45.

In the closed-circuit position of the interlupter 1, the electricalcircuit therethrough includes upper line terminal 64, relativelystationary contact 34, movable contact 31, lower extension 69 of movablecontact 31, fingers 59, tubular conductor 54, horizontal conductor 56,and the terminal stud, not shown, extending axially through the terminalbushing 7 to the outer terminal extremity 65 thereof.

To effect the opening operation of the interrupter the 55 mechanism notshown disposed within the mechanism compartment 3 is effective to effectclockwise rotation of the shaft 21 as viewed in FIG. 1. With referenceto FIG. 3B, the clockwise rotation of the internally disposed portion ofthe operating shaft 21 will cause clockwise rotation of the keyedcrank-arm 22 to effect thereby downward opening pulling movement of theoperating rods 24-. Since the upper ends of the insulating rods 24 aresecured to the outer sides of the operating puffer cylinder 2'7, thedownward opening movement of the puffer cylinder 2"! will compress gaswithin the'region 45, closing the valves 62, and forcing the compressedgas upwardly through the orifice opening 47 to effect extinction of theare 19 drawn therethrough, as shown in FIG. 4.

The first downward opening movement of the movable contact structure 31will effect separation between the relatively movable fingers 32 and theexternal side 34b of the rod-shaped stationary contact 34. The arcingcontact 33 will subsequently separate from the relatively stationarycontact 34-, so that no burning occurs upon the finger contacts 32. Theare 1% will, therefore, extend between the upper tip extremity of thearcing electrode 3-3 and the annular arc resisting portion 340 of thestationary rod contact 34. Since the gas enclosed within the casing ispreferably a highly efficient arc-extinguishing gas having a relativelyhigh dielectric strength, such as sulfur hexafluoride (SP theextinguishing action exerted upon the are if will take place veryquickly, and the are 1? will become extinguished.

With reference to FIG. 1, it will be observed that a remote circuitinterrupter 14 is connected by a transmission line 65 to the circuitinterrupter 1. The remote circuit interrupter 14 includes a pair ofstationary contacts 66 bridged by a movable contact 67, biased bygravity to an open position, and retained in the closed position by alatch 68, released by the energization of .a solenoid 69 and associatedarmature 7%. A current transformer 71 measures the current through thecircuit interrupter 14 from the line connection L The secondary windingof the current transformer '71 is connected in parallel with thesecondary winding of the current transformer 9 and also with the winding72 of a differential protective relay, generally designated by thereference numeral 73. When the differential relay '73 becomesenergizedand bridges its stationary contacts '74 by the upward movement of amovable bridging contact 75, a tripping circuit is established from thesource 76 to effect opening of the circuit interrupter l4, and alsoenergization of winding 77 tripping the circuit interrupter 1 open. Morespecifically, the rotatable shaft l is diagrammatically represented inFIG. 1. as being biased by a compression spring 78 to an open -circuitposition, and latched in the closed-circuit position by a latchingdevice 79, which is pivotally connected to a pair of armatures 8t), 81.

The winding through the differential relay 73 is responsive to thedifference of current through the line L, and the current passingthrough the circuit interrupter l, as well known by those skilled in theart. Similarly, a differential protective relay 82;, having a winding83, is also responsive to the difference of the current passing throughthe line L and the current carried by the circuit interrupter 1.Reference may be had to United States patent application, filed March31, 1958, Serial No. 725,286, new US. Patent 3,632,689, issued May 1,1962, to Benjamin P. Baker and Robert F, Karlicek, and assigned to theassignee of the instant application, for the general theory andoperation of the differential protective relays '73, 82.

it will be noted that any fault current flashing over the inside oroutside surface of the porcelain casing S, as

indicated by the fiashover conditions Q5, 95 in P165. 1,

3A and 3B, will flow to ground through the first current ransformer 8.Thus, assuming that the current is flowing in the direction of the lineL toward the circuit inter- 5 rupter l, the current transformer 71 willregister the fault current, whereas the second current transformer 9,associated with the circuit interrupter 1, will register zero current.Such a condition will cause the operation of the differential relay 73to complete the tripping circuit 98 to effect opening of the circuitinterrupters 1 and 14.

Similarly the current transformer 3 will measure full fault-producedcurre t, whereas current transformer 85, associated with remote circuitinterrupter 15, will register Zero fault-produced current. As a result,differential relay 82'. will be actuated to trip circuit breakers 1 and15. Hence all three breakers 1, 14 and 15 open under such an internalfault-condition represented by fiashover 95 or 96.

Likewise, should the current be considered as flowing from the line Lthrough the remote circuit interrupter l5 and toward the circuitinterrupter 1, the current transformer winding 85 will measure the faultcurrent, whereas the current transformer 55 will register zero currentsince the fault current reverses. its direction through the currenttransformer 8. As a consequence, differential relay 552 will pick up itscontacts 85 by the bridging member 87, and complete the tripping circuit88 to: trip the circuit interrupter f5 open as well as the circuitinterrupter 1. in addition, current transformer 9 will register thefault current, whereas current transformer 71 will register zerocurrent. Consequently, dirferential relay 73 will pick up and opencircuit interrupters l and 14. As a result, such an internal faultcondition or 96 will be sensed as an internal fault condition and willeffect tripping of both circuit interrupters 14 and 15 as well as thecircuit interrupter 1.

In a similar manner, a breakdown, as at 96, (FIGS. 1 and 3C) over theexternal surface of the porcelain casing 12 of the terminal bushing 7will pass to ground through the second current transformer 9, and, byoperation of the differential protective relays 73, 82, will insure thatbreakers 14 and 15 open as Well as. circuit interrupter 1.

From the foregoing description, it will be apparent that the particulardisposition of the first and second current transformers 8, 9,associated with the circuit interrupting assemblage 1, is such that anybreakdown, or fault condition associated with the circuit interrupter 1will pass to ground through the current transformers 8, 9 and be sensedas an internal fault condition causing circuit interrupter 1 as well asremote breakers 14, 15 to open. To insure that the fault current passesto ground through the current transformer ii, the latter has an outer,insulat ing peripheral cover 3a, to insure that if the fault strikes theupper side of the current transformer 8, it will pass to ground throughthe current transformer 8, and not externally thereof.

From the foregoing description of the invention, it will be apparentthat there is provided an improved circuitinterrupting structure of thesingle-terminal-bushing type,

in which considerable ground space is saved by the canted it will benoted that the three poles 1 of the circuit] interrupter are mountedside by side on the grounded structural steel frame 2, that elevateslive parts safely above the ground. The pole units 1 are simultaneouslyoperated by a single mechanism disposed within the mechanism compartment3, which may be of conven--' tional design. Since this mechanismcompartment 3 is situated within the supporting framework 2, the overalllength and width are held to the minimum necessary to support the poleunits.

Each pole unit 1 is comprised of a vertical porcelain column 5 housingthe interrupterstructure, and a single, canted bushing '7 of standardexternal dimensions, and of conventional condenser-type design. It willbe noted that the terminals 64, 65 for the circuit interrupter l areprovided at the top of the bushing 7 and at the top of the interruptercolumn 5. All are located in the same horizontal plane at an elevationsafely above the work area. The folded configuration of each pole unit 1avoids an unnecessarily wide, space-wasting span between the terminals64, 65. Also the adjacent pole units 1 may be spaced as closely aselectrical clearances permit, giving a compact overall arrangement.

It will be noted that there is space available for two currenttransformers in each location, resulting in a total of four currenttransformers possible per pole unit 1.

It will be noted that the stationary contact 34 is mounted beneath thedome 4i which forms the top of the vertical interrupter column 5. Belowit, in this column, is the moving contact structure 31, which comprisesan orifice, finger-type main contacts, a bayonettype arcing contact anda putter cylinder 27, supported on a pedestal 48 mounted in thepole-unit base. The moving contact structure 31 is actuated throughinsulating pull rods 24, connected to lugs 26 on the sides of the puffercylinder 27 and at the lower ends to two cranks 22 actuated by thecircuit-breaker mechanism.

As the breaker opens, downward movement of the pullrods 24 separate,successively, the main contacts and the arcing contacts, and then drawsan are 19 within the interrupting orifice 43. Gas, compressed within thecylinder 27 during the opening stroke, is forced through the orifice 43in a putt to extinguish the are 19. Current is collected from the lowerend of the moving contact structure 31 through stationary fingercontacts 59, which are, in turn, connected by a tubular conductor 54 tothe lower end of the bushing 7.

It is intended, for certain applications, that this poleunit 1 becharged with sulfur hexafiuoride (SP gas, or a similar gas of provenarc-interrupting ability. The unit 1 is essentially gas-tight inconstruction. Consequently the initial charge of gas should sufiiceuntil maintenance is required after several years of service. Thesulfur-hexafluoride gas provides dielectric strength between live partsand ground within the structure, and also serves as the arc-interruptingmedium. The drive shaft 4 is sealed at the point where it enters thepressuretype housing 6 with either a conventional O-ring type of seal,or a clamped tubular type seal, such as disclosed in United StatesPatent 2,889,434, issued June 2, 1959, to Harry J. Lingal and assignedto the assignee of the instant application.

It will be noted that the contact components are readily accessible forservicing and inspection after the gas has been bled out of thepole-unit 1. Removal of the domeshaped cover 40 at the top of thevertical column permits the stationary contact 34 to be extracted.Following this, the moving contacts may either be inspected in place, ortaken out by removing the bolts 23 that attach the assembly to theputter cylinder 27. This assembly also includes the sliding contact 60which connects with the tubular conductor 54 leading to the terminalbushing 7.

. The complete movable contact structure 31 that is supported upon thepedestal 48, excluding the stationary contact 34 supported in the dome40, may be removed from beneath the pole-unit housing 6. This is adesirable feature because the worker is located close .to ground for hisown safety, and the amount of rigging equipment is minimized. Thehorizontal conductor 56 must be disconnected at the elbow 55 at thecontact supporting post 48. Also, the contact ope-rating pull rods 24must be disconnected from the driving cranks 2 2. For these operations,access is provided through the bottom of the interrupter at the base ofthe pedestal 48 by removing the cover plate 51 on the bottom of thehousing 6. This also provides access to the pedestal mounting flange 49.Removal of bolts 4% in it permits the pedestal 48 and moving contactcomponents 31 to be lowered out of the bottom of the pole-units 1.

The vertical orientation of the interrupter column 5 affords advantagesin heat dissipation. Resistance losses cause the conducting parts toheat, and the gas surrounding these parts is, in turn, also heated.However, the tubular construction of the orifice 43, the cylinder27,;and the supporting pedestal 48 forms a chimney, which carries thesehot gases upwardly, by convection, to the dome 4i) at the top of thecolumn 5. The dome 40, being metallic, conducts the heat from thesegases outwardly to the surrounding ambient air. In necessary, thisfeature can be further enhanced by providing a larger dome 4t andequipping it with integral fins.

It is to be observed that check valves 62 have been provided at thebottom of the putter cylinder 27. In addition to permitting the passageof gas for the cooling eflect described, these valves 62 also permit thecylinder 27 to breathe in gas during the closing stroke, which has notbeen contaminated, or heated by arcing.

The particular circuit-interrupting structure 1, disclosed herein, hasthe following advantages:

(1) It provides a gas-type of circuit interrupter providing two currenttransformers or more if required per terminal.

(2) A gas-type circuit interrupter results having current transformerslocated to provide overlapping differential relay protection.

(3) A gas-type circuit interrupter providing the simplicity of a sealed,self-contained unit.

(4) A gas-type circuit interrupter arranged in a vertical column toenhance heat dissipating ability to provide high continuous currentratings.

(5) A gas-type circuit interrupter having the mechanism located forminimum overall breaker dimensions.

(6) The invention provides a gas-type circuit interrupter designed forease of inspection and maintenance.

(7) A gas-type of circuit interrupter is obtained having live partsequidistant above ground at the requisite elevation for safety.

(8) The circuit interrupter has pole units 1 of folded configuration tothereby minimize space requirements.

(9) A circuit-interrupting structures results which is simple inconstruction for economical manufacture.

Although there has been illustrated and described a specificcircuit-interrupting structure, it is to be clearly understood that thesame was merely for the purpose of illustration, and that changes andmodifications may readily be made therein by those skilled in the artwithout departing from the spirit and scope of the invention.

We claim as our invention:

1. A circuit interrupter of the single-bushing type including anupstanding insulating cylindrical interrupter housing, a relativelystationary contact disposed interiorly within the upper end of saidcylindrical interrupter housing, a longitudinally movable pufiercylinder carrying a movable contact disposed interiorly within saidcylindrical interrupter housing, the movable contact being cooperablewith the relatively stationary contact to establish an arc, the movementof the putter cylinder forcing fluid under pressure toward theestablished arc to effect the extinction thereof, a grounded mechanismhousing disposed below said upstanding cylindrical interrupter housingand serving to support the same, a canted terminal bushing ofconventional type supported by said grounded mechanism housing, theangle between the axial center lines of the interrupter housing and theterminal bushing being less than 180, and a removable cover platesecured to the bottom of the mechanism housing to effect downwardwithdrawal of the movable puffer cylinder for service and maintenance.

the same, interrupting elements disposed Within said hollow casing forestablishing and extinguishing an arc, a canted terminal bushingsupported by said grounded support housing, a pair of currenttransformers, one of said current transformers being disposed below thehollow casing so that any fault to ground over the casing will pass toground through said one current transformer and the sensed as aninternal fault, the other current transformer being mounted upon saidgrounded support housing in such relation to the protruding end of theterminal bushing that any breakdown over the external end of theterminal bushing will be sensed as an internal fault.

3. The combination in a single-bushing type of circuit interrupter of anupstanding hollow insulating interrupter casing, a grounded supporthousing disposed below said hollow insulating interrupter casing andserving to support the same, a relatively stationary contact disposedwithin the upper end of the hollow casing, a movable contact cooperablewith the relatively stationary contact to establish an arc, a movablepuffer cylinder carrying said movable contact and operable to force ablast of fluid under pressure at the established arc to effect theextinction thereof, a canted terminal bushing supported by said groundedsupport housing, a pair of current transformers, one of said currenttransformers being disposed below the hollow casing so that any fault toground over the casing will pass to ground through said one currenttransformer and be sensed as an internal fault, the other currenttransformer being mounted upon said grounded support housing in suchrelation to the protruding end of the terminal bushing that anybreakdown over the external end of the terminal bushing will be sensedas an internal fault.

4. A circuit interrupter of the single-bushing type including anupstanding insulating cylindrical interrupter housing, a relativelystationary contact disposed interiorly Within the upper end of saidcylindrical interrupter hous ing, a longitudinally movable puffercylinder carrying a movable contact disposed interiorly within saidcylindrical interrupter housing, the movable contact being cooperablewith the relatively stationary contact to establish an arc, the movementof the puffer cylinder forcing fluid under pressure toward theestablished arc to effect the extinction thereof, a grounded mechanismhousing disposed below said upstanding cylindrical interrupter housingand serving to support the same, a canted terminal bushing ofconventional type supported by said grounded mechanism housing, and theangle between the axial center lines of the interrupter housing and theterminal bushing being less than 180, crank means disposed within saidmechanism housing, and longitudinally extending operating-rod meansinterconnecting said crank means and said longitudinally movable puffercylinder, and a removable cover plate secured to the bottom of themechanism housing to effect downward withdrawal of the movable puttercylinder for service and maintenance.

5. A circuit interrupter of the single-bushing type including aninsulating cylindrical interrupter housing, a relatively stationarycontact disposed interiorly within the upper end of said cylindricalinterrupter housing, a longitudinally movable putter cylinder carrying amovable contact disposed interiorly within said cylindrical interrupterhousing, the movable contact being cooper-able with the relativelystationary contact to establish an arc, the movement of the puffercylinder forcing fluid under pressure toward the established arc toeffect the extinction thereof, a grounded mechanism housing disposedbelow said cylindrical interrupter housing and serving to support thesame, a canted terminal bushing of conventional type supported by saidgrounded mechanism housing and making an angle with the axial centerline of the interrupter housing, and a removable cover plate secured tothe bottom of the mechanism housing to effect downward withdrawal of themovable puifer cylinder for service and maintenance.

6. The combination in a single-bushing type of circuit interrupter of ahollow insulating interrupter casing, a grounded support housingdisposed below said hollow insulating interrupter casing and serving tosupport the same, interrupting elements disposed within said hollowcasing for establishing and extinguishing an arc, a canted terminalbushing supported by said grounded support housing, a pair of currenttransformers, one of said current transformers being disposed below thehollow casing so that any fault to ground over the casing will pass toground through said one current trans-former and be sensed as aninternal fault, the other current transformer being mounted upon saidgrounded support housing in such relation to the protruding end of theterminal bushing that any breakdown over the external end of theterminal bushing will be sensed as an internal fault.

7. The combination in a single bushing type of circuit interrupter of ahollow insulating interrupter casing, a grounded support housingdisposed below said hollow insulating interrupter casing and serving tosupport the same, a relatively stationary contact disposed within theupper end of the hollow casing, a movable contact cooperable with therelatively stationary contact to establish an arc, a movable puffercylinder carrying said movable contact and operable to force a blast offiuid under pressure at the established arc to effect the extinctionthereof, a canted terminal bushing supported by said grounded supporthousing, a pair of current transformers, one of said currenttransformers being disposed below the hollow casing so that any fault toground over the casing will pass to ground through said one currenttransformer and be sensed as an internal fault, the other currenttransformer being mounted upon said grounded support housing in suchrelation to the protruding end of the terminal bushing that anybreakdown over the external end of the terminal bushing will be sensedas an internal fault.

References Cited in the file of this patent UNITED STATES PATENTS2,445,529 Leeds July 20, 1948 2,488,569 Strom Nov. 22, 1949 2,707,740Zuhlke May 3, 1955 2,709,737 Forwald May 31, 1955 2,766,348 Forwald Oct.9, 1956 2,804,576 Coggeshall Aug. 27, 1957 2,866,045 Leeds Dec. 23, 19582,913,556 Leeds Nov. 17, 1959 2,979,591 Friedrich Apr. 11, 19613,114,815 Easley et al Dec. 17, 1963 FOREIGN PATENTS 505,668 GreatBritain May 16, 1939 534,936 Great Britain Mar. 24, 1941 535,956 GreatBritain Apr. 28, 1941 550,151 Great Britain Dec. 24, 1942 655,585Germany Jan. 19, 1938

1. A CIRCUIT INTERRUPTER OF THE SINGLE-BUSHING TYPE INCLUDING ANUPSTANDING INSULATING CYLINDRICAL INTERRUPTER HOUSING, A RELATIVELYSTATIONARY CONTACT DISPOSED INTERIORLY WITHIN THE UPPER END OF SAIDCYLINDRICAL INTERRUPTER HOUSING, A LONGITUDINALLY MOVABLE PUFFERCYLINDER CARRYING A MOVABLE CONTACT DISPOSED INTERIORLY WITHIN SAIDCYLINDRICAL INTERRUPTER HOUSING, THE MOVABLE CONTACT BEING COOPERABLEWITH THE RELATIVELY STATIONARY CONTACT TO ESTABLISH AN ARC, THE MOVEMENTOF THE PUFFER CYLINDER FORCING FLUID UNDER PRESSURE TOWARD THEESTABLISHED ARC TO EFFECT THE EXTINCTION THEREOF, A GROUNDED MECHANISMHOUSING DISPOSED BELOW SAID UPSTANDING CYLINDRICAL INTERRUPTER HOUSINGAND SERVING TO SUPPORT THE SAME, A CANTED TERMINAL BUSHING OFCONVENTIONAL TYPE SUPPORTED BY SAID GROUNDED MECHANISM HOUSING, THEANGLE BETWEEN THE AXIAL CENTER LINES OF THE INTERRUPTER HOUSING AND THETERMINAL BUSHING BEING LESS THAN 180*, AND A REMOVABLE COVER PLATESECURED TO THE BOTTOM OF THE MECHANISM HOUSING TO EFFECT DOWNWARDWITHDRAWAL OF THE MOVABLE PUFFER CYLINDER FOR SERVICE AND MAINTENANCE.